Structural chemistry and solvent properties of dimethylsulfoxide

An examination of the chemical environment and structure of dimethylsulfoxide (DMSO) in the solid state leads to a description of its bonding properties that is useful in proposing structures for solvation complexes in DMSO solutions. The O atom acts as a type A (hard) Lewis base of strength similar to or somewhat greater than that of water and is capable of bonding to metal cations with oxidation states between+1 and+3. The methylprotons are weakly acid and are found to form bonds to weak bases such as ClO4−, NO3−, and halogen ions. DMSO is an ideal solvent for compounds of strongly acid cations and weakly basic anions.Bonding alos occurs through S to type-B (soft) Lewis acids (groups 8–10) particularly when the soft Lewis acid is already coordinated to electron donor groups. In these cases the oxygen basicity is dependent on the electron donating or withdrawing power of the type-B acid.